Field
The disclosed concept relates generally to electrical systems that employ distributed power sources, and, in particular, to a system and method for adjusting the trip characteristics of a circuit breaker in an electrical system having current limited distributed power sources, such as a branch circuit that includes one or more current limited distributed power sources and, in some instances, one or more loads.
Background Information
A distributed power source is a small-scale power generation mechanism used to provide an alternative to or an enhancement of the traditional electric power system. Distributed power sources include, for example and without limitation, photovoltaic (PV) modules, wind turbine modules, backup generators, energy storage, and uninterruptible power supplies.
The National Electric Code (NEC) presently requires a distributed power source to be located on a dedicated branch circuit (i.e. without any loads on the same branch circuit or subpanel). This is done to ensure that the circuit breaker for that branch circuit is rated to protect the branch circuit wiring from any overcurrent conditions, regardless of the power source.
It would be advantageous to be able to use existing electrical infrastructure (panel boards, load centers, wiring, etc.) to locate and connect current limited distributed power sources on the same (non-dedicated) branch circuit as loads. This would be of particular interest for distributed generation systems and microgrids as well as for Building Integrated PV (BIPV) systems which include microinverters typically in the form of distributed plug inverters (DPIs). The problem is that in such a configuration, the trip curve of the branch circuit breaker, which determines the amount of time required for the circuit breaker to trip at a given overcurrent level, needs to be adjusted to compensate for the distributed power sources being present on the same non-dedicated circuit (e.g., plugged into receptacles). Currently, there is no efficient way for making such adjustments.